a) Field of the Invention
The present invention relates to a semiconductor integrated circuit device, and more particularly to a semiconductor integrated circuit device effective for achieving high-speed operation in a semiconductor integrated circuit device, and to a method for the manufacture thereof.
The speed of signal propagation through multilayer wiring in a semiconductor integrated circuit is determined by the resistance of the lines and the parasitic capacitance between lines. In highly integrated semiconductor integrated circuits, the line pitch (line and space) is small, resulting in higher parasitic capacitance between lines. The parasitic capacitance between lines in a given wiring layer can be reduced by making the lines thinner, but making the lines thinner increases resistance in the lines, with the result that large scale semiconductor integrated circuit device operating speeds cannot be achieved.
In order to reduce parasitic capacitance without making the lines thinner, it is necessary to reduce the dielectric constant of the interlayer dielectric films. Where the line spacing is 0.5 .mu.m or smaller, the interlayer insulating film dielectric constant is a significant factor controlling the signal propagation delay, and can be expected to affect semiconductor integrated circuit device performance.
b) Description of the Related Art
The interlayer dielectric films used in semiconductor integrated circuit devices are predominantly silicon dioxide films, phosphosilicate glass (PSG), which are deposited through chemical vapor deposition (CVD). The relative dielectric constant of such films varies with the conditions under which a film is formed; that of silicon thermal oxidation films, which have the lowest dielectric constant, is on the order of 4.0. Insulating films formed by spin-on-glass coating (SOG films) are highly hygroscopic and have relative dielectric constants of 5 or higher.
In recent years, polymeric materials consisting of Teflon (polytetrafluoroethylene) or hydrocarbon, have attracted attention as low-dielectric constant insulating materials. Teflon materials, however, are somewhat impractical in terms of heat resistance and low adhesion with other materials. Hydrocarbon materials are also somewhat impractical since they are readily oxidized and absorb moisture if oxidized, resulting in fluctuations in the dielectric constant.
Attempts have been made to reduce the dielectric constant by introducing fluorine atoms into an inorganic film deposited by CVD. However, the introduction of fluorine atoms in large amounts increases the hygroscopic, so the dielectric constant that can be achieved in actual practice is on the order of 3.5.